I can't tell from your avie enough to score it, but inside spread doesn't really add much to an overall score anyway. (The difference between 20" and 15" obviously is only 5 points, but add 2"-4" per beam and 1" to every scorable point and mass measurement and suddenly the score grows considerably!) My best scoring buck is a 14ptr from southern MO that was officially scored at 154" and change yet is only 13.5" inside. He scores from length and mass, a true "basket rack".
As far as "what is an average trophy" or what is big depends greatly on 2 things, your experience and what part of the area you mostly hunt in. When I was 14 years old any legal buck short of a spindly spike bit the dust. Now as a 40 year old with many deer notched I don't pick up the bow or gun unless 140-150" is standing nearby. When I hunted in KS and south TX the minimums went up substantially.
What you'd probably pull the trigger on in Saskatchewan or Iowa is far different than what you'd probably pull the trigger on in the swamps of Florida or South Carolina. Some areas produce 150" bucks at 3 years old, some places it takes 5+ years yet some places seldom even produce such bucks!
YOU have to determine what a trophy is FOR YOU. A 4+ year old buck IS a trophy nearly anywhere he lives, regardless of his headgear. I've seen 4yr old 150" bucks on south TX ranches that had hardly ever had much human interaction yet a 120" 4yr old buck in PA or NY is MUCH more cagey and "the survivor" than his Texan cousin!
HL